The human eye is known to naturally evolve with time. This includes aging effects, eye surgery or can result from accidents or from exposure to atypical or harmful environmental conditions. This evolution may change the geometry of the eye optics, the dynamics of its operation and its accommodative capacity. Age-related eye changes are described for example in “Age-Related Changes of the Human Eye” by Carlo A. P. Cavallotti, Luciano Cerulli, 2008, Springer. Changes in the geometry of the eye optics (e.g., thickness of the crystalline lens, its position, etc.) may be also provoked by various interventions, such as intra ocular surgery or a Lasik operation. Obviously, those interventions have the goal to improve the vision. However the uncontrolled (post-surgery or age related) changes are generally degrading the vision.
One of the possible ways of addressing this problem is the repeated surgical intervention, which may create further complication or simply be impossible. Another way of proceeding is to test the vision at different time scales and to order corresponding glasses or contact lenses if it is in principle possible to correct the resulting refractive errors.
An interesting alternative way was proposed that is based on the light adjustable lens (LAL), see, for example, J Refract Surg. 2010 October; 26(10):716-21. doi: 10.3928/1081597X-20100408-02. Epub 2010 Apr. 15. Evaluation of the Calhoun Vision UV Light Adjustable Lens implanted following cataract removal. Hengerer F H, Conrad-Hengerer I, Buchner S E, Dick H B. This may be an intra-ocular lens (IOL) that is composed of UV sensitive material. In this case, the lens is inserted in the eye (during the cataract surgery) and the patients are asked to wear UV protective glasses. After few weeks, the refractive analysis of patients has identified the refractive errors to be corrected. This was done by the exposition of IOL (the LAL) by UV light. The material of the LAL is photopolymerized causing the shape and hence the power of the lens to change. In principle this operation may be repeated one or two times. However, the LAL is finally “locked” and no more modifications are possible.
While this is a very interesting approach. It still remains rather difficult (and not user friendly) and also its reprogramming capacity is very limited in time.
Various accommodative IOLs have also been proposed, which are based on the dynamic (multiple time) mechanical deformation of the shape of the lens, of the distance between two lenses (composing the IOL) and also some non-mechanical (electrically variable) lenses. In an article entitled “Accommodating IOLs: Emerging Concepts and Designs” published July 2004 in Cataract & Refractive Surgery Today, Samuel Masket MD describes such lenses and difficulties in characterizing a crystalline lens in situ, which is subject to forces exerted by adjoining tissues, leading to an inability to create an implant having desired properties under forces exerted by adjoining tissues postoperatively.
The tunable liquid crystal lens (TLCL) technology is an emerging technology that is suitable for IOL applications. The present applicant, LensVector, manufactures a TLCL product as detailed at http://lensvector.com/wp-content/uploads/2014/04/Gen3-Product-Brief-V1.pdf.